Accelerated simulation solving method and system for controllable self-recovery energy dissipation device

Abstract

The invention provides an accelerated simulation solving method and system for a controllable self-recovery energy dissipation device, and the method comprises the steps: S1, enabling an inductance element between a nonlinear network and a linear network in a hybrid cascade DC power transmission system to be equivalent to a short transmission line, and building circuit models for the linear network and the nonlinear network respectively; s2, obtaining the value of the current controlled voltage source based on the node voltage of the previous simulation time step of the linear and nonlinear networks, the value of the controlled voltage source and the information interaction format; s3, node voltage solving is carried out based on the value of the controlled voltage source of the current simulation time step to obtain the node voltage of the current simulation time step, if the number of iterations is met, the operation is stopped, and otherwise, the step S2 is executed; the nonlinear network comprises a controllable self-recovery energy dissipation device; according to the invention, the energy dissipation device and the linear main circuit in the circuit system are decoupled in a sub-network manner, the calculation amount is reduced, and the iterative algorithm is used for solving, so that the high-efficiency and high-precision simulation of a nonlinear network and a linear network is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic transient simulation of power equipment, and particularly relates to an accelerated simulation solution method and system for a controllable self - recovering energy dissipation device. Background Technique

[0002] The hybrid HVDC transmission technology based on traditional DC and flexible DC combines the advantages of long transmission distance, large transmission power, low cost of LCC transmission, and flexible controllability and strong reactive power support ability of VSC. It is an important development direction for DC transmission technology and new - energy supply and consumption. At the sending - end, LCC is adopted, and at the receiving - end, the hybrid cascaded HVDC transmission technology with LCC and VSC arranged at the same station has the transmission capacity and dynamic reactive power support ability of multi - landing hybrid cascaded HVDC, and also has the function of regulating the transmission power of the AC channel. When a short - circuit fault occurs in the receiving - end AC system, the energy transmission will be blocked, and it is difficult for the sending - end to respond quickly in a short time, which will cause power surplus and may damage the equipment. To avoid equipment damage during a fault, a transient energy consumption device needs to be configured in the hybrid cascaded HVDC transmission system.

[0003] The main component of the energy dissipation device is a lightning arrester, and the lightning arrester is a non - linear element. At present, there are usually three methods for electromagnetic transient solution of non - linear elements: current - source substitution method, piece - wise linear method, and iterative solution method. The current - source substitution method introduces a delay of one simulation step, and there may be numerical stability problems; the piece - wise linear method model is easy to implement, but numerical instability will be caused due to improper handling of the correction process when the section changes during the solution; the iterative solution method has high solution accuracy and numerical stability, but for the overall solution of a network containing non - linear elements, it will occupy a large amount of simulation resources, with an excessive amount of calculation and affect the simulation efficiency. Summary of the Invention

[0004] To overcome the deficiencies of the above - mentioned prior art, the present invention proposes an accelerated simulation solution method for a controllable self - recovering energy dissipation device, including:

[0005] S1. By equivalently replacing the inductance element connecting the non - linear network and the linear network in the hybrid cascaded HVDC transmission system with a short transmission line, circuit models of the non - linear network and the linear network are respectively established;

[0006] S2. Based on the node voltages and the values of the controlled voltage sources at the previous simulation time step of the linear network and the non - linear network, and in combination with the information interaction format between the linear network and the non - linear network, the value of the controlled voltage source at the current simulation time step is obtained;

[0007] S3. Solve the nodal voltages in the electromagnetic transient simulation processes of the linear network and the non - linear network respectively based on the values of the controlled voltage sources at the current simulation time step of the linear network and the non - linear network, to obtain the nodal voltages of the linear network and the non - linear network at the current simulation time step. If the preset number of iterations is satisfied, stop; otherwise, jump to step S2;

[0008] The non - linear network includes a controllable self - recovering energy - dissipating device, and the linear network includes the other parts of the hybrid cascaded HVDC transmission system where the controllable self - recovering energy - dissipating device is located.

[0009] Optionally, solving the nodal voltages in the electromagnetic transient simulation process of the non - linear network based on the value of the controlled voltage source at the current simulation time step of the non - linear network to obtain the nodal voltages of the non - linear network at the current simulation time step includes:

[0010] Based on the admittances of the nodes and components in the non - linear network, the equivalent wave impedance of the short transmission line, and the value of the controlled voltage source at the current simulation time step, combined with the nodal voltage iterative formula of the Newton - Raphson iteration method, obtain the nodal voltages of the non - linear network at the current simulation time step.

[0011] Optionally, the nodal voltage iterative formula of the Newton - Raphson iteration method is:

[0012]

[0013] where, u n+1 represents the nodal voltage of the non - linear network at the current simulation time step; u n represents the nodal voltage of the non - linear network at the previous simulation time step; f(u n ) represents the non - linear equation in the electromagnetic transient simulation process of the non - linear network; represents the partial derivative of the non - linear equation with respect to the nodal voltage.

[0014] Optionally, the non - linear equation is:

[0015] f(u)=Gu - I ar (u)-I s = 0

[0016] where, f(u) represents the non - linear equation in the electromagnetic transient simulation process of the non - linear network; G represents the admittance matrix of the nodes in the non - linear network; u represents the nodal voltage of the non - linear network; I ar represents the current of the components in the non - linear network; I s represents the nodal injection current of the non - linear network; the nodal injection current is obtained by the ratio of the values of the controlled voltage source of the non - linear network and the other power sources in the circuit model to the equivalent wave impedance of the short transmission line.

[0017] Optionally, the calculation formula for the partial derivative of the non-linear equation with respect to the node voltage is:

[0018]

[0019] Wherein, represents the partial derivative of the non-linear equation with respect to the node voltage; G represents the admittance matrix of the nodes in the non-linear network; represents the admittance of the components in the non-linear network.

[0020] Optionally, the information interaction format between the non-linear network and the linear network is:

[0021]

[0022] Wherein, represents the value of the controlled voltage source in the linear network circuit model at the (n + 1)-th simulation time step; represents the value of the controlled voltage source in the non-linear network circuit model at the n-th simulation time step; represents the value of the controlled voltage source in the non-linear network circuit model at the (n + 1)-th simulation time step; represents the value of the controlled voltage source in the linear network circuit model at the n-th simulation time step; represents the port voltage of the non-linear network circuit model at the n-th simulation time step; represents the port voltage of the non-linear network circuit model at the n-th simulation.

[0023] Optionally, the port voltages in the circuit models of the linear network and the non-linear network are obtained respectively according to the node voltages in their respective circuit models and the topological structure of the circuit model.

[0024] Optionally, equivalent the inductance element connecting the non-linear network and the linear network in the hybrid cascaded HVDC system to a short transmission line, including:

[0025] Introduce a capacitor to the inductance element connecting the non-linear network and the linear network in the hybrid cascaded HVDC system, and equivalent the inductance element with the introduced capacitor to a short transmission line with a transmission delay of one simulation step;

[0026] The value of the introduced capacitor is obtained by combining the simulation step and the value of the inductance element with the equivalent capacitance calculation formula.

[0027] Based on the same inventive concept, the present invention proposes an accelerated simulation solution system for a controllable self-recovery energy dissipation device, including:

[0028] A network separation module, configured to respectively establish their own circuit models for the non-linear network and the linear network by equivalenting the inductance element connecting the non-linear network and the linear network in the hybrid cascaded HVDC system to a short transmission line;

[0029] An information interaction module, which is used to obtain the value of the controlled voltage source at the current simulation time step based on the node voltages and the values of the controlled voltage sources at the previous simulation time step on the linear network and the non-linear network, and in combination with the information interaction format between the linear network and the non-linear network;

[0030] A node voltage solving module, which is used to solve the node voltages in the electromagnetic transient simulation processes of the linear network and the non-linear network respectively based on the values of the controlled voltage sources at the current simulation time step of the linear network and the non-linear network, obtain the node voltages of the linear network and the non-linear network at the current simulation time step, and stop if the preset number of iterations is satisfied, otherwise call the information interaction module;

[0031] The non-linear network includes a controllable self-restoring energy dissipation device, and the linear network includes other parts of the hybrid cascaded HVDC transmission system where the controllable self-restoring energy dissipation device is located.

[0032] Optionally, in the node voltage solving module, solving the node voltages in the electromagnetic transient simulation process of the non-linear network based on the value of the controlled voltage source at the current simulation time step of the non-linear network to obtain the node voltages of the non-linear network at the current simulation time step includes:

[0033] Based on the admittances of the nodes and components in the non-linear network, the equivalent wave impedance of the short transmission line, and the value of the controlled voltage source at the current simulation time step, and in combination with the node voltage iterative formula of the Newton-Raphson iteration method, obtain the node voltages of the non-linear network at the current simulation time step.

[0034] Optionally, the node voltage iterative formula of the Newton-Raphson iteration method in the node voltage solving module is:

[0035]

[0036] where, u n+1 represents the node voltage of the non-linear network at the current simulation time step; u n represents the node voltage of the non-linear network at the previous simulation time step; f(u n ) represents the non-linear equation in the electromagnetic transient simulation process of the non-linear network; represents the partial derivative of the non-linear equation with respect to the node voltage.

[0037] Optionally, the non-linear equation of the node voltage solving module is:

[0038] f(u) = Gu - I ar (u) - I s = 0

[0039] Among them, f(u) represents the non - linear equation of the electromagnetic transient simulation process of the non - linear network; G represents the admittance matrix of the nodes in the non - linear network; u represents the node voltage of the non - linear network; I ar represents the current of the components in the non - linear network; I s represents the node injection current of the non - linear network; the node injection current is obtained by the ratio of the values of the controlled voltage source in the non - linear network and other power sources in the circuit model to the equivalent wave impedance of the short transmission line.

[0040] Optionally, in the node voltage solving module, the calculation formula for the partial derivative of the non - linear equation with respect to the node voltage is:

[0041]

[0042] Among them, represents the partial derivative of the non - linear equation with respect to the node voltage; G represents the admittance matrix of the nodes in the non - linear network; represents the admittance of the components in the non - linear network.

[0043] Optionally, the information interaction format between the non - linear network and the linear network in the information interaction module is:

[0044]

[0045] Among them, represents the value of the controlled voltage source in the linear network circuit model at the (n + 1) - th simulation time step; represents the value of the controlled voltage source in the non - linear network circuit model at the n - th simulation time step; represents the value of the controlled voltage source in the non - linear network circuit model at the (n + 1) - th simulation time step; represents the value of the controlled voltage source in the linear network circuit model at the n - th simulation time step; represents the port voltage of the non - linear network circuit model at the n - th simulation time step; represents the port voltage of the non - linear network circuit model at the n - th simulation.

[0046] Optionally, in the information interaction module, the port voltages in the circuit models of the linear network and the non - linear network are obtained respectively according to the node voltages in their respective circuit models and the topological structure of the circuit model.

[0047] Optionally, in the network splitting module, the inductance element connecting the non - linear network and the linear network in the hybrid cascaded HVDC system is equivalent to a short transmission line, including:

[0048] A capacitor is introduced to the inductance element connecting the non - linear network and the linear network in the hybrid cascaded HVDC system, and the inductance element with the introduced capacitor is equivalent to a short transmission line with a transmission delay of one simulation step.

[0049] Compared with the closest prior art, the beneficial effects of the present invention are as follows:

[0050] An accelerated simulation solution method and system for a controllable self - recovery energy - dissipating device proposed by the present invention include: S1. By equivalenting the inductance element connecting the non - linear network and the linear network in the hybrid cascaded HVDC system to a short transmission line, circuit models of the non - linear network and the linear network are respectively established; S2. Based on the node voltages and the values of the controlled voltage sources at the previous simulation time step of the linear network and the non - linear network, and combining the information interaction format between the linear network and the non - linear network, the value of the controlled voltage source at the current simulation time step is obtained; S3. Based on the values of the controlled voltage sources at the current simulation time step of the linear network and the non - linear network, the node voltages in the electromagnetic transient simulation process of the linear network and the non - linear network are respectively solved to obtain the node voltages at the current simulation time step of the linear network and the non - linear network. If the preset number of iterations is satisfied, stop; otherwise, jump to step S2; the non - linear network includes a controllable self - recovery energy - dissipating device, and the linear network includes other parts of the hybrid cascaded HVDC system where the controllable self - recovery energy - dissipating device is located; in this application, the energy - dissipating device and the linear main circuit in the circuit system are decoupled by network. Compared with the overall solution of the network containing non - linear elements, the amount of calculation is reduced. The non - linear network is solved by the iterative method, ensuring high - efficiency and high - precision simulation of the controllable self - recovery energy - dissipating device and the linear network. Description of the Drawings

[0051] Figure 1 It is a schematic flow chart of an accelerated simulation solution method for a controllable self - recovery energy - dissipating device provided by the present invention;

[0052] Figure 2 It is a topological structure diagram of a controllable self - recovery energy - dissipating device;

[0053] Figure 3 It is a schematic structural diagram of a linear network and a non - linear network connected by an inductance element;

[0054] Figure 4 It is a schematic structural diagram of an equivalent circuit after the equivalent transmission line is divided by network;

[0055] Figure 5 It is a schematic diagram of the original circuit;

[0056] Figure 6 It is a schematic diagram of the original circuit with a small inductance inserted;

[0057] Figure 7Schematic diagram of the equivalent circuit after subnetting in the test example;

[0058] Figure 8 Schematic diagram of the current change of the energy dissipation device during simulation solution;

[0059] Figure 9 Schematic diagram of the voltage change of the energy dissipation device during simulation solution;

[0060] Figure 10 Schematic diagram of the structure of an accelerated simulation solution system for a controllable self - recovering energy dissipation device provided by the present invention. Detailed implementation manners

[0061] The following further elaborates on the detailed implementation manners of the present invention with reference to the accompanying drawings.

[0062] Embodiment 1:

[0063] An accelerated simulation solution method for a controllable self - recovering energy dissipation device provided by the present invention, as Figure 1 shown, includes:

[0064] S1. By equivalenting the inductance element connecting the nonlinear network and the linear network in the hybrid cascaded HVDC system to a short transmission line, circuit models are respectively established for the nonlinear network and the linear network;

[0065] S2. Based on the node voltages and the values of the controlled voltage sources at the previous simulation time step of the linear network and the nonlinear network, and combining the information interaction format between the linear network and the nonlinear network, the value of the controlled voltage source at the current simulation time step is obtained;

[0066] S3. Based on the values of the controlled voltage sources at the current simulation time step of the linear network and the nonlinear network, the node voltages in the electromagnetic transient simulation process of the linear network and the nonlinear network are respectively solved to obtain the node voltages of the linear network and the nonlinear network at the current simulation time step. If the preset number of iterations is satisfied, stop; otherwise, jump to step S2;

[0067] The nonlinear network includes a controllable self - recovering energy dissipation device, and the linear network includes other parts of the hybrid cascaded HVDC system where the controllable self - recovering energy dissipation device is located.

[0068] The hybrid cascaded HVDC system in step S1 includes a linear network and a nonlinear network part. The nonlinear network includes a controllable self - recovering energy dissipation device, and the linear network includes other parts of the hybrid cascaded HVDC system where the controllable self - recovering energy dissipation device is located.

[0069] The controllable self - recovering energy dissipation device is connected in parallel to the MMC converter station in the hybrid cascaded HVDC system, and the topological structure of the controllable self - recovering energy dissipation device is as Figure 2As shown, it consists of a lightning arrester (including a fixed part MOA1 and a controllable part MOA2, and both MOA1 and MOA2 are composed of multiple columns of lightning arresters connected in parallel), and a switch. MOA represents a lightning arrester. Figure 2 In Figure 2 , the "fixed part" refers to the fixed part, and the "controllable part" refers to the controllable part. When the system is in normal operation, the switch K is in the open state, and the entire lightning arrester is put into operation. When a fault occurs in the system, the switch K receives the closing command issued by the control and protection system, bypasses the controllable part MOA2, thereby limiting the overvoltage of the MMC and protecting the MMC sub-module.

[0070] Since the hybrid cascaded DC transmission system contains non-linear elements, namely lightning arresters, to reduce the computational complexity of the iterative solution of the entire system, this application uses the sub-network method to separately solve the non-linear elements and the linear network.

[0071] A capacitor is introduced to the inductance element connecting the non-linear network and the linear network in the hybrid cascaded DC transmission system. The inductance element with the introduced capacitor is equivalent to a short transmission line with a transmission delay of one simulation step, as Figure 3 shown; separate circuit models are established for the non-linear network and the linear network respectively, as Figure 4 shown.

[0072] The value of the introduced capacitor is obtained by combining the simulation step, the value of the inductance element, and the equivalent capacitance calculation formula.

[0073] Specifically, the following formula is used to calculate the equivalent transmission distance of one simulation step:

[0074]

[0075] where, Δl represents the equivalent transmission distance of one simulation step; v represents the signal transmission speed; Δt represents one simulation step; L d represents the inductance per unit equivalent distance; C d represents the capacitance per unit equivalent distance.

[0076] The relationship between the inductance element and the inductance per unit equivalent distance is expressed by the following formula:

[0077] L d Δl = L (2)

[0078] where, L represents the inductance of the inductance element; L d represents the inductance per unit equivalent distance.

[0079] From formula (1) and formula (2), the calculation formula for the capacitance per unit equivalent distance can be obtained as:

[0080]

[0081] Calculate the equivalent wave impedance of the equivalent short transmission line according to the following formula:

[0082]

[0083] where, Z L represents the equivalent wave impedance of the equivalent short transmission line.

[0084] The calculation formula for the equivalent capacitance obtained from Equations (1) - (4) is:

[0085]

[0086] where, C e represents the equivalent capacitance of the equivalent short transmission line; Δt represents a simulation time step, that is, the time of a simulation time step; L represents the value of the inductor element.

[0087] By introducing the capacitance C e the inductor element L is equivalent to a short transmission line with a transmission delay of one simulation time step. Since the simulation time step is very small, the value of C e is very small and is usually a stray parameter.

[0088] By equivalent the inductor to a short transmission line, the electromagnetic transient simulations of linear networks and nonlinear networks can be solved separately, and information interaction is carried out through two controlled voltage sources. Figure 4 V1 and V2 in

[0089] In step S2, based on the node voltages and the values of the controlled voltage sources of the linear network and the nonlinear network at the previous simulation time step, combined with the information interaction format between the linear network and the nonlinear network, the value of the controlled voltage source at the current simulation time step is obtained. The information interaction format between the linear network and the nonlinear network is:

[0090]

[0091] where, represents the value of the controlled voltage source in the linear network circuit model at the (n + 1)-th simulation time step; represents the value of the controlled voltage source in the nonlinear network circuit model at the n-th simulation time step; represents the value of the controlled voltage source in the nonlinear network circuit model at the (n + 1)-th simulation time step; represents the value of the controlled voltage source in the linear network circuit model at the n-th simulation time step; represents the port voltage of the nonlinear network circuit model at the n-th simulation time step; represents the port voltage of the nonlinear network circuit model at the n-th simulation.

[0092] The port voltages in the circuit models of the linear network and the nonlinear network are obtained respectively according to the node voltages in their respective circuit models and the topological structure of the circuit models.

[0093] In step S3, based on the values of the controlled voltage sources at the current simulation time step of the linear network and the nonlinear network, the node voltages in the electromagnetic transient simulation processes of the linear network and the nonlinear network are solved respectively to obtain the node voltages of the linear network and the nonlinear network at the current simulation time step. If the preset number of iterations is satisfied, stop; otherwise, jump to step S2.

[0094] Specifically, it includes solving the node voltages in the electromagnetic transient simulation process of the linear network:

[0095] G1u1 = I s1 -I h1 (7)

[0096] Among them, G1 represents the admittance of the nodes in the linear network; u1 represents the node voltages in the linear network; I s1 represents the injected current of the nodes in the linear network; I h1 represents the historical current of the nodes in the linear network.

[0097] The node voltages in the electromagnetic transient simulation process of the nonlinear network (controllable self - recovery energy - dissipating device system) are solved by using the node voltage method, and the solution formula is:

[0098] Gu = I ar (u)+I s (8)

[0099] Among them, G represents the admittance matrix of the nodes in the nonlinear network; u represents the node voltages of the nonlinear network; I ar (u) represents the current of the nonlinear elements in the nonlinear network, that is, the current of the arrester; I s represents the injected current of the nodes in the nonlinear network.

[0100] The injected current of the nodes is generated jointly by the controlled voltage source and the ideal power source, and the injected current of the nodes is obtained by the ratio of the values of the controlled voltage source and the ideal power source to the equivalent wave impedance of the short transmission line.

[0101] The Newton - Raphson iteration method is used to solve the nonlinear network, and a nonlinear equation for iterative solution using the Newton - Raphson method is constructed. The nonlinear equation is:

[0102] f(u)=Gu - I ar (u)-I s = 0 (9)

[0103] Among them, f(u) represents the nonlinear equation in the electromagnetic transient simulation process of the nonlinear network.

[0104] Based on the admittances of nodes and components in the nonlinear network, the equivalent wave impedance of the short transmission line, and the value of the controlled voltage source at the current simulation time step, combined with the node voltage iterative formula of the Newton-Raphson iteration method, the node voltage at the current simulation time step of the nonlinear network is obtained. The node voltage iterative formula is as follows:

[0105]

[0106] where, u n+1 represents the node voltage of the nonlinear network at the current simulation time step, that is, the vector of node voltage estimated values, i.e.; u n represents the node voltage in the nonlinear network at the previous simulation time step; f(u n ) represents the nonlinear equation in the electromagnetic transient simulation process of the nonlinear network; represents the partial derivative of the nonlinear equation with respect to the node voltage.

[0107] The initial voltage of the node is preset to 0. At each iteration step, a new node voltage is obtained.

[0108] The partial derivative of the nonlinear equation with respect to the node voltage is represented by the Jacobian matrix of the nonlinear equation:

[0109]

[0110] where, J represents the Jacobian matrix of the nonlinear equation; represents the partial derivative of the nonlinear equation with respect to the node voltage; G represents the admittance matrix of nodes in the nonlinear network; represents the admittance of components in the nonlinear network, that is, the admittance of the arrester.

[0111] The admittance of components in the nonlinear network is obtained by interpolation according to the volt-ampere characteristic curve of the components, that is, the admittance of the arrester is obtained by interpolation according to the volt-ampere characteristic curve of the arrester.

[0112] Using the Newton-Raphson iteration method to solve the nonlinear network ensures the high-efficiency and high-precision simulation of the controllable self-recovery energy dissipation device and the linear network.

[0113] Embodiment 2

[0114] The present invention is verified by a test case. As Figure 5 shown is the original circuit schematic diagram of this test case. Among them, the value of the capacitor C is 1 mF. The capacitor is used to provide an initial voltage for the circuit in the test case and discharge the resistor; the initial voltage is 530 kV, and the value of the resistor R is 1 Ω. When t = 0.1 s, the switch K changes from the off state to the on state. MOA1 and MOA2 respectively represent the fixed part and the controllable part of the arrester. A small inductor of 1 mH is inserted between the capacitor and the controllable energy dissipation device. AsFigure 6 As shown Figure 6 the 1, 1’, 2, 2’ in [reference] and those in Example 1 Figure 3 correspond to the nodes

[0115] Using the network partitioning method in Example 1, by equivalenting the small inductor to a short transmission line with a transmission delay of one simulation step, the circuit in the test case is divided into a linear network and a non - linear network. The equivalent circuit is as Figure 7 shown Figure 7 In [figure], ① and ② in the linear network respectively represent the first node and the second node, and there is only one node ① in the non - linear network

[0116] Calculate the equivalent wave impedance of the short transmission line according to the following formula

[0117]

[0118] where, Z L represents the equivalent wave impedance; Δt represents the simulation step, and the simulation step is 5 μs; L represents the inductor. Solve the node voltage for the electromagnetic transient simulation process of the linear network

[0119] G1u1 = I s1 -I h1

[0120] where, G1 represents the admittance of the node in the linear network u1 represents the node voltage in the linear network; I s1 represents the node injection current in the linear network V1 represents the value of the controlled voltage source; I h1 represents the historical current of the node I c represents the historical current of the capacitor, I c = u1(1)*0.005; 0.005 is obtained by the ratio of the step size 5 μs to the capacitor 1 mF; u1(1) represents the node voltage of the first node in the linear network

[0121] There is only one node in the non - linear network, so the node admittance matrix is of the first order. The node voltage, node injection current, and non - linear element current are all one - dimensional vectors, and the dimension of each parameter depends on the number of nodes in the network

[0122] The node voltage iterative formula for the non - linear network is

[0123]

[0124] where, u n+1 represents the node voltage estimated value vector at the current simulation time step, that is, the node voltage; u nrepresents the vector of estimated values of node voltages at the previous simulation time step; f(u n ) represents the non - linear equation in the electromagnetic transient simulation process of the non - linear network; represents the partial derivative of the non - linear equation with respect to the node voltage.

[0125] In this test case, it is necessary to find the vector of estimated values of node voltages u n+1 at the current simulation time step, which is denoted as u(1) in this embodiment, and u n is a known quantity obtained at the previous simulation time step; f(u)=Gu - I ar (u)-I s , where G represents the admittance of nodes in the non - linear network, G = [0.005],

[0126] is obtained through the Jacobian matrix:

[0127]

[0128] that is, J = 0.005 - G ar ; G ar and I ar (u) represent the admittance and current of the non - linear arrester respectively, and G ar and I ar (u) are obtained according to the voltage across the arrester and the volt - ampere characteristic curve.

[0129] Information interaction between the linear network and the non - linear network is carried out according to the following formula:

[0130]

[0131] where, represents the value of the controlled voltage source in the linear network circuit model at the (n + 1) - th simulation time step; represents the value of the controlled voltage source in the linear network circuit model at the n - th simulation time step; u1(1) represents the node voltage of the first node in the linear network circuit at the n - th simulation time step, u1(2) represents the node voltage of the second node in the linear network circuit at the n - th simulation time step, and (u1(1)-u1(2)) represents the port voltage of the linear network circuit model at the n - th simulation time step; represents the value of the controlled voltage source in the non - linear network circuit model at the (n + 1) - th simulation time step; represents the value of the controlled voltage source in the non - linear network circuit model at the n - th simulation time step; u1(1) represents the voltage of the node in the non - linear network at the n - th simulation time, and according to the circuit topology, this node voltage is the port voltage of the non - linear network circuit model at the n - th simulation time.

[0132] The simulation results obtained in this test case are asFigure 8 and Figure 9 as shown Figure 8 which is a schematic diagram of the current change of the energy dissipation device, where the vertical axis is the current of the energy dissipation device and the horizontal axis is time; Figure 9 which is a schematic diagram of the voltage change of the energy dissipation device during simulation solving, where the vertical axis is the voltage of the energy dissipation device and the horizontal axis is time; Figure 8 and Figure 9 The curves in and respectively represent the simulation results using the pscad software without dividing the linear network and the nonlinear network (before pscad division), the simulation results using the pscad software after dividing the linear network and the nonlinear network (after pscad division), and the simulation results using the method provided by the present application after dividing the linear network and the nonlinear network. It can be seen from the figure that the method provided by the present application has high accuracy.

[0133] Embodiment 3

[0134] Based on the same inventive concept, the present invention provides an accelerated simulation solving system for a controllable self - restoring energy dissipation device, as Figure 10 shown, including:

[0135] A network - dividing module, configured to respectively establish circuit models for the nonlinear network and the linear network by equivalently replacing the inductance element connecting the nonlinear network and the linear network in the hybrid - cascaded HVDC system with a short transmission line;

[0136] An information interaction module, configured to obtain the value of the controlled voltage source at the current simulation time step based on the node voltages and the values of the controlled voltage sources at the previous simulation time step of the linear network and the nonlinear network, in combination with the information interaction format between the linear network and the nonlinear network;

[0137] A node voltage solving module, configured to solve the node voltages in the electromagnetic transient simulation process of the linear network and the nonlinear network respectively based on the values of the controlled voltage sources at the current simulation time step of the linear network and the nonlinear network, to obtain the node voltages of the linear network and the nonlinear network at the current simulation time step. If the preset number of iterations is satisfied, stop; otherwise, call the information interaction module;

[0138] The nonlinear network includes a controllable self - restoring energy dissipation device, and the linear network includes other parts of the hybrid - cascaded HVDC system where the controllable self - restoring energy dissipation device is located.

[0139] In the node voltage solving module, solving the node voltages in the electromagnetic transient simulation process of the nonlinear network based on the value of the controlled voltage source at the current simulation time step of the nonlinear network to obtain the node voltages of the nonlinear network at the current simulation time step includes:

[0140] Based on the admittances of nodes and components in the nonlinear network, the equivalent wave impedance of the short transmission line, and the value of the controlled voltage source at the current simulation time step, combined with the node voltage iterative formula of the Newton-Raphson iteration method, the node voltage at the current simulation time step of the nonlinear network is obtained.

[0141] The node voltage iterative formula of the Newton-Raphson iteration method in the node voltage solving module is:

[0142]

[0143] where, u n+1 represents the node voltage of the nonlinear network at the current simulation time step; u n represents the node voltage of the nonlinear network at the previous simulation time step; f(u n ) represents the nonlinear equation in the electromagnetic transient simulation process of the nonlinear network; represents the partial derivative of the nonlinear equation with respect to the node voltage.

[0144] The nonlinear equation of the node voltage solving module is:

[0145] f(u) = Gu - I ar (u) - I s = 0

[0146] where, f(u) represents the nonlinear equation in the electromagnetic transient simulation process of the nonlinear network; G represents the admittance matrix of nodes in the nonlinear network; u represents the node voltage of the nonlinear network; I ar represents the current of components in the nonlinear network; I s represents the node injection current in the nonlinear network; the node injection current is obtained by the ratio of the values of the controlled voltage source of the nonlinear network and other power sources in the circuit model to the equivalent wave impedance of the short transmission line.

[0147] In the node voltage solving module, the calculation formula for the partial derivative of the nonlinear equation with respect to the node voltage is:

[0148]

[0149] where, represents the partial derivative of the nonlinear equation with respect to the node voltage; G represents the admittance matrix of nodes in the nonlinear network; represents the admittance of components in the nonlinear network.

[0150] The information interaction format between the nonlinear network and the linear network of the information interaction module is:

[0151]

[0152] where, represents the value of the controlled voltage source in the linear network circuit model at the (n + 1)-th simulation time step; represents the value of the controlled voltage source in the non - linear network circuit model at the n - th simulation time step; represents the value of the controlled voltage source in the non - linear network circuit model at the (n + 1)-th simulation time step; represents the value of the controlled voltage source in the linear network circuit model at the n - th simulation time step; represents the port voltage of the non - linear network circuit model at the n - th simulation time step; represents the port voltage of the non - linear network circuit model during the n - th simulation.

[0153] In the information interaction module, the port voltages in the circuit models of the linear network and the non - linear network are obtained respectively according to the node voltages in their respective circuit models and the topological structures of the circuit models.

[0154] In the network - splitting module, the inductance element connecting the non - linear network and the linear network in the hybrid cascaded HVDC system is equivalent to a short transmission line, including:

[0155] Introduce a capacitor to the inductance element connecting the non - linear network and the linear network in the hybrid cascaded HVDC system, and the inductance element with the introduced capacitor is equivalent to a short transmission line with a transmission delay of one simulation step;

[0156] The value of the introduced capacitor is obtained by combining the simulation step, the value of the inductance element, and the equivalent capacitance calculation formula.

[0157] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer - usable storage media (including but not limited to disk memory, CD - ROM, optical memory, etc.) containing computer - usable program code.

[0158] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, and the combination of processes and / or blocks in the flowcharts and / or block diagrams can be realized by computer program instructions. These computer program instructions can be provided to the processors of general - purpose computers, special - purpose computers, embedded processors, or other programmable data - processing devices to generate a machine, so that the instructions executed by the processors of the computer or other programmable data - processing devices generate for realizing in the process Figure 1 one process or multiple processes and / or blocks Figure 1means for the functions specified in one or more boxes.

[0159] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in one Figure 1 process or more processes and / or boxes Figure 1 or more boxes.

[0160] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operational steps are performed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one Figure 1 process or more processes and / or boxes Figure 1 or more boxes.

[0161] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit the scope of its protection. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that after reading the present invention, various changes, modifications or equivalent replacements can still be made to the specific implementation manners of the application. However, these changes, modifications or equivalent replacements are all within the scope of the protection of the claims pending for the application.

Claims

1. A method for accelerating simulation and solution of a controllable self - recovering energy dissipation device, characterized in that Including: S1. By equivalenting the inductance element connecting the non-linear network and the linear network in the hybrid cascaded HVDC transmission system to a short transmission line, circuit models are respectively established for the non-linear network and the linear network; S2. Based on the node voltages and the values of the controlled voltage sources at the previous simulation time step of the linear network and the non-linear network, and combining the information interaction format between the linear network and the non-linear network, the values of the controlled voltage sources at the current simulation time step are obtained; S3. Based on the values of the controlled voltage sources at the current simulation time step of the linear network and the non-linear network, the node voltages in the electromagnetic transient simulation process of the linear network and the non-linear network are respectively solved to obtain the node voltages of the linear network and the non-linear network at the current simulation time step. If the preset number of iterations is satisfied, stop; otherwise, jump to step S2; The non-linear network includes a controllable self-recovery energy dissipation device, and the linear network includes other parts of the hybrid cascaded HVDC transmission system where the controllable self-recovery energy dissipation device is located.

2. The accelerated simulation solution method of a controllable self - restoring energy dissipation device according to claim 1, characterized in that, Based on the value of the controlled voltage source at the current simulation time step of the non-linear network, solving the node voltage in the electromagnetic transient simulation process of the non-linear network to obtain the node voltage of the non-linear network at the current simulation time step includes: Based on the admittances of the nodes and components in the non-linear network, the equivalent wave impedance of the short transmission line, and the value of the controlled voltage source at the current simulation time step, and combining the node voltage iterative formula of the Newton-Raphson iteration method, the node voltage of the non-linear network at the current simulation time step is obtained.

3. The accelerated simulation solution method of a controllable self - restoring energy dissipation device according to claim 2, characterized in that, The node voltage iterative formula of the Newton-Raphson iteration method is: Among them, u n+1 represents the node voltage of the nonlinear network at the current simulation time step; u n represents the node voltage of the nonlinear network at the previous simulation time step; f(u n ) represents the nonlinear equation of the electromagnetic transient simulation process of the nonlinear network; represents the partial derivative of the nonlinear equation with respect to the node voltage.

4. The accelerated simulation solution method of a controllable self - recovering energy dissipation device as described in claim 3, characterized in that, The non-linear equation is: f(u) = Gu - I ar (u) - I s = 0 Among them, f(u) represents the non - linear equation of the electromagnetic transient simulation process of the non - linear network; G represents the admittance matrix of the nodes in the non - linear network; u represents the node voltage of the non - linear network; I ar represents the current of the components in the non - linear network; I s represents the node injection current in the non - linear network, and the node injection current is obtained by the ratio of the values of the controlled voltage source of the non - linear network and other power sources in the circuit model to the equivalent wave impedance of the short transmission line.

5. The accelerated simulation solution method of a controllable self - restoring energy dissipation device according to claim 3, characterized in that, The calculation formula for the partial derivative of the non-linear equation with respect to the node voltage is: Among them, represents the partial derivative of the nonlinear equation with respect to the node voltage; G represents the admittance matrix of the nodes in the nonlinear network; represents the admittance of the components in the nonlinear network.

6. The accelerated simulation solution method of a controllable self - restoring energy dissipation device according to claim 1, characterized in that, The information interaction format between the non-linear network and the linear network is: Among them, represents the value of the controlled voltage source in the linear network circuit model at the (n + 1)-th simulation time step; represents the value of the controlled voltage source in the non-linear network circuit model at the n-th simulation time step; represents the value of the controlled voltage source in the non-linear network circuit model at the (n + 1)-th simulation time step; represents the value of the controlled voltage source in the linear network circuit model at the n-th simulation time step; represents the port voltage of the non-linear network circuit model at the n-th simulation time step; represents the port voltage of the non-linear network circuit model at the n-th simulation.

7. The accelerated simulation solution method of a controllable self - recovering energy dissipation device according to claim 6, characterized in that, The port voltages in the circuit models of the linear network and the non-linear network are respectively obtained according to the node voltages in their respective circuit models and the topological structure of the circuit models.

8. The accelerated simulation solution method of a controllable self - restoring energy dissipation device according to claim 1, characterized in that, Equivalenting the inductance element connecting the non-linear network and the linear network in the hybrid cascaded HVDC transmission system to a short transmission line includes: Introducing a capacitor to the inductance element connecting the non-linear network and the linear network in the hybrid cascaded HVDC transmission system, and equivalenting the inductance element with the introduced capacitor to a short transmission line with a transmission delay of one simulation step; The value of the introduced capacitor is obtained by combining the simulation step and the value of the inductance element with the equivalent capacitance calculation formula.

9. An accelerated simulation solution system for a controllable self - restoring energy dissipation device, characterized in that, Including; A network separation module for respectively establishing circuit models for the non-linear network and the linear network by equivalenting the inductance element connecting the non-linear network and the linear network in the hybrid cascaded HVDC transmission system to a short transmission line; An information interaction module for obtaining the values of the controlled voltage sources at the current simulation time step based on the node voltages and the values of the controlled voltage sources at the previous simulation time step of the linear network and the non-linear network, and combining the information interaction format between the linear network and the non-linear network; A node voltage solving module for respectively solving the node voltages in the electromagnetic transient simulation process of the linear network and the non-linear network based on the values of the controlled voltage sources at the current simulation time step of the linear network and the non-linear network to obtain the node voltages of the linear network and the non-linear network at the current simulation time step. If the preset number of iterations is satisfied, stop; otherwise, call the information interaction module; The non-linear network includes a controllable self-restoring energy dissipation device, and the linear network includes other parts of the hybrid cascaded HVDC transmission system where the controllable self-restoring energy dissipation device is located.

10. The acceleration simulation solution system of a controllable self - recovering energy dissipation device according to claim 9, characterized in that, In the node voltage solving module, based on the value of the controlled voltage source at the current simulation time step of the non-linear network, the node voltage in the electromagnetic transient simulation process of the non-linear network is solved to obtain the node voltage at the current simulation time step of the non-linear network, including: Based on the admittances of the nodes and components in the non-linear network, the equivalent wave impedance of the short transmission line, and the value of the controlled voltage source at the current simulation time step, combined with the node voltage iterative formula of the Newton-Raphson iteration method, the node voltage at the current simulation time step of the non-linear network is obtained.

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